Climate change imposes new environmental conditions on plant communities resulting in new plant assemblages made up of species able to survive the new conditions. Successful restoration efforts take into consideration future climate conditions, proactively planning by using plants predicted to thrive under future conditions. Identifying sources of such plants is challenging given the scarcity of such genetic information.
Bryce Richardson, Gerald Rehfeldt and Elizabeth Milano, from USDA-Forest Service,Moscow, Idaho, in collaboration with Cuauhtémoc Sáenz-Romero, developed a modeling tool able to locate contemporary sites with climate analogs similar to what would occur by mid-century (~2060) at target locations for reforestation (see "A climate analog approach to evaluate seed transfer and vegetation transitions" in Publications). In other words, their modeling tool identifies sites where seeds collected today are likely to be adapted to future climates at target monarch overwintering reforestation sites.
As part of this work, their model was applied to Monera Alta, a site in the core zone of the MBBR located at Ejido Cerro Prieto, historically a site occupied by overwintering monarch colonies but severely damaged by the winter storm of March 2016 and in need of restoration. The modeling tool identified the contemporary composition of tree species as well as what could be the species composition in the future given new climate conditions. According to model results, today oyamel (Abies religiosa) would dominate the stand composition (83% of the trees) and by mid-century, the climate would be suitable for a composition of only 47% oyamel with a substantial increase in the probability of other pine species (53% of Pinus pseudostrobus) currently occurring at lower elevation. Thus, the appropriate seed source to conduct reforestations at Monera Alta, compatible with its future climate, are located today at about 500 m lower elevation than Monera Alta.
The model also pinpoints potential new sites for establishing monarch overwintering sites at higher elevations. At sites with much higher elevation than the MBBR, such as the forest of the Calimaya indigenous community at Nevado de Toluca, on a site at 3800m elevation, contemporary forest composition is predicted by the modeling tool as being dominated by Pinus hartwegii (86%), the timberline pine. However, that high elevation pine species drops to 50% by middle of the century, and the probability for oyamel (A. religiosa) jumps from 0% at present to 67%. This site is, in fact, part of the MBF-funded assisted migration field test sites.
Dr. Sáenz-Romero notes that all predictions of present forest species compositions are completely in accord with current field observations, both at Monera Alta and at Nevado de Toluca, giving the team great confidence that they are on the right track with assisted migration experiments involving A. religiosa from the MBBR at Nevado de Toluca (see video below).